Ion exchange cobalt recovery

ABSTRACT

Method of ion exchange cobalt recovery. Raffinate including cobalt, zinc, copper, nickel and ferric iron is produced. In the raffinate, the pH is raised, the solids are removed and ferric iron is reduced. A copper recovery ion exchange unit is loaded with ion exchange resin selective for copper. Raffinate is fed into the copper recovery ion exchange unit which is regenerated to recover substantially all copper. A cobalt/nickel/zinc recovery ion exchange unit is loaded with another ion exchange resin selective for cobalt. Raffinate is fed into the cobalt/nickel/zinc recovery ion exchange unit, the ion exchange resin holding cobalt, zinc and nickel, and then displaced. Cobalt/zinc eluent is fed into the cobalt/zinc/nickel recovery ion exchange unit to elute the cobalt and zinc in a cobalt/zinc solution, and then displaced. Nickel eluent is fed into the cobalt/zinc/nickel recovery ion exchange unit to elute the nickel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional U.S. Patent applicationSer. No. 61/303,022, filed Feb. 10, 2010, which is incorporated byreference as though fully set forth herein.

FIELD OF INVENTION

This invention relates to methods for extracting metals from raw oregenerally and more specifically to processes for recovering cobalt fromcopper solvent extraction raffinate with ion exchange technology.

BACKGROUND OF THE INVENTION

In mining operations, raw ore contains metals of value that arerecoverable. Several known techniques, including solvent extraction(“SX”) are used to chemically separate metals from raw ore. In SX, metalions, for example, copper ions, are leached or otherwise extracted fromraw copper ore using chemical agents, such as strong acid. The copper isthen plated out of solution onto stainless steel sheets usingelectrowinning (“EW”) processes. Cobalt, a naturally occurring valuablemetal, is added to many copper EW tankhouses to reduce not onlycorrosion of insoluble lead anodes but also the overvoltage of theoxygen evolution from the anodes. The byproduct of SX is raffinate inwhich certain metals, including cobalt, may remain after the metal ofprimary interest, e.g., copper, is extracted from the pregnant leachsolution (“PLS”).

BRIEF SUMMARY OF THE INVENTION

The following summary is provided as a brief overview of the claimedmethod and apparatus. It should not limit the invention in any respect,with a detailed and fully-enabling disclosure being set forth in theDetailed Description of the Invention section. Likewise, the inventionshall not be restricted to any numerical parameters, processingequipment, chemical reagents, operational conditions, and othervariables unless otherwise stated herein.

According to one embodiment of the present invention, a method of ionexchange cobalt recovery from raffinate, comprises: producing raffinatethat includes at least cobalt, zinc, copper, nickel and ferric iron;raising a pH of the raffinate; removing solids from the raffinate;reducing ferric iron to ferrous iron; loading a copper recovery ionexchange unit with an ion exchange resin selective for copper; feedingthe raffinate into the copper recovery ion exchange unit in a firstdirection; regenerating the copper recovery ion exchange unit to recoversubstantially all the copper from the ion exchange resin selective forcopper; loading a cobalt/nickel/zinc recovery ion exchange unit with asecond ion exchange resin selective at least for cobalt; feeding theraffinate into the cobalt/nickel/zinc recovery ion exchange unit in thefirst direction, the second ion exchange resin holding cobalt, zinc andnickel; displacing the raffinate from the cobalt/nickel/zinc recoveryion exchange unit; feeding cobalt/zinc eluent into thecobalt/zinc/nickel recovery ion exchange unit to elute the cobalt andzinc in a cobalt/zinc solution; displacing the cobalt/zinc eluent in thecobalt/zinc/nickel recovery ion exchange unit; and feeding nickel eluentinto the cobalt/zinc/nickel recovery ion exchange unit to elute thenickel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, which are incorporated herein and form a partof the specification, illustrate various embodiments of the presentinvention and, together with the description, serve to explain theinvention. In the figures:

FIG. 1 is a flow sheet illustrating apparatus of the present inventionfor recovering cobalt and nickel from raffinate;

FIG. 2 is a flow sheet illustrating apparatus of the present inventionfor recovering cobalt, zinc and nickel from raffinate;

FIG. 3 is a flow sheet illustrating apparatus of the present inventionfor recovering cobalt, zinc and nickel from raffinate;

FIG. 4 is a flow sheet illustrating apparatus of the present inventionfor recovering cobalt, zinc and nickel from raffinate;

FIG. 5 illustrates an embodiment of a method for recovering copper,nickel and cobalt from raffinate;

FIG. 6 illustrates an embodiment of a method for recovering copper,nickel, cobalt and zinc from raffinate;

FIG. 7 is a graph showing affinities of bispicolylamine resin forvarious metals at different pH levels;

FIG. 8 is a graph showing copper recovery according to one embodiment ofthe invention;

FIG. 9 shows graphs of the loading and elution of metals from Example 1according to an embodiment of the present invention;

FIG. 10 shows graphs of the loading and elution of metals from Example 3according to an embodiment of the present invention;

FIG. 11 shows graphs of the loading and elution of metals from Example 4according to an embodiment of the present invention;

FIG. 12 is a of the elution of metals from Example 5 according to anembodiment of the present invention;

FIG. 13 shows graphs of the loading and elution of metals from Example 6according to an embodiment of the present invention;

FIG. 14 shows graphs of the loading and elution of metals from Example10 according to an embodiment of the present invention;

FIG. 15 is a graph showing loading and elution of metals from Example 11according to an embodiment of the present invention;

FIG. 16 is a graph showing copper loading in Example 12 according to anembodiment of the present invention;

FIG. 17 is a graph showing copper elution in Example 12 according to anembodiment of the present invention;

FIG. 18 is a graph showing copper elution in Example 12 according to anembodiment of the present invention; and

FIG. 19 is a graph showing copper elution in Example 12 according to anembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Although SX performs well in extracting copper from PLS, it is not anefficient or economical method for recovering cobalt from mine leach orraffinate 13 streams. Cobalt concentration in raffinate 13 is so dilutethat the SX method cannot be used for extraction. Also, aluminuminterferes with SX by generating a large amount of crud in theextraction stages.

The present invention provides a means for recovering cobalt and othermetals using a combination of SX and ion exchange methods, which mayyield significant operational metal. By recovering cobalt and othermetals, these metals may be recycled into the SX process. Therefore, itmay be desirable to remove cobalt and other metals from raffinate 13using the apparatus 10 and method 100 of the present invention.

The present invention comprises apparatus 10 and method 100 forextracting cobalt from raffinate 13 using ion exchange and elutionprocesses as are described more fully below. Apparatus 10 and method 100of the present invention may be a function of the various constituentsof raffinate 13, which may depend not only on the constituents of themetal ore, but also on the reagents used during SX. In one embodiment,raffinate 13 comprises at least copper, cobalt, nickel, iron (ferrousand ferric). In other embodiments, raffinate 13 may also comprise any orall of ferrous iron, magnesium or zinc.

Various embodiments of apparatus 10 will now be described with referenceto the drawing figures. In an embodiment shown in FIG. 1 in which theraffinate 13 comprises at least copper, cobalt, nickel, magnesium andiron, apparatus 10 comprises pretreatment system 11, ion exchange system19, and eluate system 23.

Pretreatment system 11 allows raffinate 13 to be pretreated by adjustingthe pH level and reducing iron, to prepare raffinate 13 for the ionexchange processes. As shown in FIG. 1, pretreatment system 11 comprisesraffinate tank 12, process tank 14 and drum filter 16. In anotherembodiment, in which raffinate 13 comprises organic, pretreatment 11 mayalso include vessel(s) (not shown) for organic removal using adsorbentresins or chelating resins or a combination as may be appropriate giventhe total organic carbon composition of raffinate 13.

Raffinate tank 12 is sized to receive raffinate 13 generated throughcopper SX. Raffinate tank 12 is fluidically connected to process tank14. As used herein, “fluidically connected” means connected using pipes,conduits, valves, pumps and other similar apparatus that provide for themovement of fluid in systems of this type. Once raffinate 13 leavesraffinate tank 12, raffinate 13 enters process tank 14, which is sizedto receive, not only raffinate 13, but also other reagents to aid in theprocesses to be performed in process tank 14. As mentioned above, inprocess tank 14, the pH of raffinate 13 may be adjusted and iron may bereduced. In the embodiment shown in FIG. 1, in process tank 14, the pHof raffinate 13 may be raised from between about 1.45 to about 1.8 toabout 3.0 to about 3.5, preferably about 3.0 to about 3.2, in processtank 14, by adding calcium oxide (CaO), calcium carbonate (CaCO₃) orother similar reagents contained in a vessel (not shown) connected toprocess tank 14. Depending on the composition of raffinate 13 involved,in other embodiments, pH may be adjusted up or down to obtain thedesired pH, as would be familiar to one of ordinary skill in the artafter becoming familiar with the teachings of this invention; in otherembodiments, the pH may not need to be adjusted at all. In theembodiments disclosed herein, the desired pH is in the range of about3.0 to about 3.5, preferably between about 3.0 and about 3.2; based onthe ion exchange resins used, a different pH may be preferred.

In the embodiment shown in FIG. 1, raising the pH by adding addition ofCaO produces solids requiring removal to minimize clogging of ionexchange system 19. These solids may be removed using a variety ofcommercially available coagulants and flocculents, such as Nalco N8850coagulant and N7871 flocculent, which may be added to process tank 14following pH adjustment. The coagulant and flocculent are commerciallyavailable from Nalco Company, Tempe Ariz. The coagulants and flocculentsmay be contained in a vessel (not shown) connected to process tank 14.The coagulated solids may then be removed by filtering, such as byrunning raffinate 13 through drum filter 16 which is fluidicallyconnected to process tank 14 to receive the solids removed from processtank 14. Other known mechanical separation processes may be used toseparate the coagulated solids from raffinate 13. In another embodiment,an additional filter (e.g., inline cartridge filter (not shown)) may beadded to apparatus 10 immediately upstream of copper removal ionexchange unit 18.

In addition to pH level adjustment, iron reduction may also take placein the process tank 14, as in the embodiment illustrated in FIG. 1. Asexplained more fully below, iron reduction may be beneficial given theaffinities for ferric iron or ferrous iron of the various ion exchangeresins selected for the process. See FIG. 7. In the embodiment shown inFIG. 1, iron reduction from ferric iron to ferrous iron is achieved byaddition of sodium sulfite (Na₂SO₃) or other similar reagents, which maybe contained in a vessel (not shown) connected to process tank 14.Alternatively, an intermediate tank for iron reduction or otherprocesses may be provided before raffinate 13 enters ion exchange system19. Of course, if the raffinate 13 contains only ferrous iron, noreduction is necessary.

Once raffinate 13 has been pretreated 105 according to embodiments ofthe present invention, pretreated raffinate 13 enters ion exchangesystem 19 which is fluidically connected to process tank 14. In theembodiment shown in FIG. 1, ion exchange system 19 comprises copperremoval ion exchange unit 18 and cobalt/nickel removal ion exchange unit22, both of which comprise multiple resin columns which may be arrangedin fixed beds of lead-lag configuration or in carousel or otherconfigurations as would be familiar to one of ordinary skill in the artafter becoming familiar with the teachings of the present invention.

In another embodiment, ion exchange system 19 may comprisecobalt/nickel/zinc removal ion exchange unit 15. See FIGS. 2-4. Inembodiments described herein, copper removal precedes cobalt/nickelremoval from raffinate 13 because the bispicolylamine functionalized ionexchange resin that has a high affinity for cobalt and nickel also has ahigh affinity for copper. See FIG. 8. Copper can contaminate thebispicolylamine resin, a chelating resin, by loading the resinpreferentially, requiring ammonia solutions (as opposed to strong acidsolution) to strip out the copper. Therefore, as shown in FIG. 1, copperremoval ion exchange unit 18 is upstream of cobalt/nickel ion exchangeunit 22 in apparatus 10.

Copper removal ion exchange unit 18 may be a fixed bed system loadedwith an ion exchange resin with a high affinity for copper, such as ahydroxypropylpicolylamine functionalized resin, a chelating resin withhigh affinity for copper at low pH (e.g., between about 3.0 to about3.5) that can be stripped using strong acid solutions; it iscommercially available as XUS-43605 from The Dow Chemical Company;however, other similar resins could also be used. The fixed bed systemmay be comprise multiple beds in a lead-lag configuration, as shown inFIG. 1, comprising lead (first) column 21 and lag (second) column 25(although the designation of lead and lag may change during processingdepending on which column is primarily loaded with copper). In variousembodiments, copper removal ion exchange unit 18 may comprise two,three, four or more beds. Process tank 14 is fluidically connected tothe top of the lead column 21, so that raffinate 13 may be pumped intothe top of lead column 21, exiting the bottom of lead column 21 andentering the top of lag column 25. Copper removal ion exchange unit 18loaded with ion exchange resin selective for copper removessubstantially all copper in raffinate 13. “Substantially all” means fromabout 95% to about 100% of the copper in raffinate 13. Preferably, allcopper is removed, so that the raffinate 13 exiting the bottom of thelag column 25 is copper-free. As is explained in more detail below,copper may be stripped and the beds (e.g., lead column 21 and lag column25) regenerated using copper eluent comprising sulfuric acid (H₂SO₄) ora lean electroyte (containing copper and strong acid, such as H₂SO₄). Inan embodiment comprising lead column 21 and lag column 25, regenerationmay be accomplished countercurrent to the direction of loading with a20% H₂SO₄ solution. See FIG. 1. Copper eluent may be contained in coppereluent tank 17, which is part of eluent system 23 and is fluidicallyconnected to copper removal ion exchange unit 18. The copper isrecovered as copper sulfate (CuSO₄) in solution which is removed tocopper recovery vessel. Copper recovery vessel 20 is fluidicallyconnected to copper removal ion exchange unit 18. Copper recovery vessel20 may comprise an intermediate tank or the actual copper EW tankhouse.

Raffinate 13 is then conveyed to cobalt/nickel removal ion exchange unit22 which is fluidically connected to copper removal ion exchange unit18. Cobalt/nickel removal ion exchange unit 22 may be a fixed bed systemcomprising multiple columns loaded with an ion exchange resin with ahigh affinity for both cobalt and nickel, such as bispicolylaminefunctionalized ion exchange resin which is commercially available asXUS-43578 from The Dow Chemical Company, although other similar resinsmay also be used.

After full loading of the columns with nickel and cobalt, nickel andcobalt are stripped by means of eluate system 23. In addition to coppereluent tank 17, eluate system 23 comprises cobalt eluent tank 24 andnickel eluent tank 26. Cobalt eluent tank 31 and nickel eluent tank 29are fluidically connected to cobalt/nickel removal ion exchange unit 22so that, at the appropriate point, either cobalt eluent or nickel eluentcan be added to the cobalt/nickel removal ion exchange unit 22 to stripeither cobalt or nickel from the loaded resin. Since cobalt does notadhere as strongly to the resin as nickel, cobalt may be consideredeasier to remove than nickel, using an acid concentration weaker thanthat required to strip the nickel. Therefore in the embodiment shown inFIGS. 1-4, cobalt is removed first. Cobalt eluent tank 31 is sized forholding cobalt eluent which comprises H₂SO₄ in concentration of about 2%to about 4%, preferably between 2.5% to 3.85%, although weakconcentrations of other strong acids may also be used. As used herein“strong acid” means hydrochloric acid (HCl), nitric acid (HNO₃) andperchloric acid (HClO₄), as well as H₂SO₄. With the addition of cobalteluent from cobalt eluent tank 31 to the cobalt/nickel removal ionexchange unit 22, cobalt is stripped from the resin and conveyed insolution to cobalt eluate tank 24.

In an embodiment wherein raffinate 13 comprises zinc, eluate system 23further comprises cobalt/zinc eluent tank 27, as shown in FIGS. 2 and 3.Cobalt/zinc eluent tank 27 is fluidically connected to cobalt/nickelremoval ion exchange unit 22, which in the embodiment being describedalso removes zinc using the second ion exchange resin (e.g.,bispicolylamine functionalized ion exchange resin). Cobalt/zinc eluenttank 27 is sized for holding cobalt/zinc eluent comprising H₂SO₄ inconcentration of about 2% to about 4% by volume, preferably between 2.5%to 3.85% by volume, although weak concentrations of other strong acidscould be used. Cobalt/zinc eluent may be the same substance as cobalteluent described above. Cobalt and zinc are stripped out together usingcobalt/zinc eluent and are conveyed in solution to cobalt/zinc eluatetank 28. From there, cobalt may be stripped using various methods as aredescribed below.

Nickel is next removed. Nickel eluent tank 29 is sized for holdingnickel eluent which comprises H₂SO₄ in concentration of about 20% byvolume or 200 g/L, although other high concentrations of strong acidcould also be used. With the addition of nickel eluent from nickeleluent tank 31 to the cobalt/nickel removal ion exchange unit 22, nickelis stripped from the resin and conveyed in solution to nickel eluatetank 26.

Depending on the metals to be recovered from raffinate 13, in anotherembodiment of the invention, eluate system 23 may also compriseadditional eluent and eluate tanks fluidically connected to ion exchangesystem 19. Additional eluent tanks, such as cobalt/zinc eluent tank 27,may hold eluent for stripping desired metals from ion exchange resin.Additional eluate tanks, such as cobalt/zinc eluate tank 28, may beprovided to recover such metals in solution. Similarly, depending on theparticular embodiment of method 100 carried out, apparatus 10 may alsocomprise additional vessels, including rinse, barren, feed, eluent andeluate tanks, including barren tank 30, nickel eluent rinse water tank36 and mass balance tank 34.

With reference to FIGS. 2 and 3, other embodiments of apparatus 10 willnow be described. Although apparatus 10 comprises process tank 14, drumfilter 16, copper ion exchange unit 18, copper eluent tank 17 and copperremoval vessel 20, FIGS. 2 and 3 focus on ion exchange system 19 andeluate system 23. See also FIG. 4. In the embodiments shown, apparatus10 comprises raffinate tank 12 which is sized for holding raffinate 13(e.g., 400 gallons). Raffinate 13 in this embodiment comprises zinc orzinc and magnesium, as well as cobalt, nickel and ferrous iron, thecopper having already been removed and the iron having already beenreduced. As shown in FIGS. 2-4, mass balance tank 34′ is fluidicallyconnected to raffinate tank 12 so that raffinate 13 may be analyzedprior to the point at which raffinate 13 enters cobalt/nickel/zincremoval ion exchange unit 15; however, mass balance tank 34′ is notrequired. Raffinate tank 12 is also fluidically connected tocobalt/nickel/zinc removal ion exchange unit 15, specifically a firstset of five columns 151 that is a part of the cobalt/nickel/zinc removalion exchange unit 15. In another embodiment of the invention,cobalt/nickel/zinc removal ion exchange unit 15 may be fluidicallyconnected to and receive raffinate 13 from copper removal ion exchangeunit 18.

As shown in FIG. 2-4, raffinate 13 is then conveyed (e.g., pumped) fromraffinate tank 12 to cobalt/nickel/zinc removal ion exchange unit 15,which comprises a carousel equipped with 24 columns 151-159 loaded withan ion exchange resin with a high affinity for both cobalt and nickel,such as bispicolylamine functionalized ion exchange resin. The carouselis also connected to a multiple port valve (not shown), which enablesthe carousel to be fluidically connected to other systems, making itpart of eluate system 23, as well. The carousel configuration thereforepermits loading, rinsing and eluting without changing vessels. Themultiple port valve may also be operatively associated with a timer, sothat apparatus 10 can be operated automatically. Other configurationsfor the cobalt/nickel/zinc ion exchange unit 15 are also possible.

Since raffinate tank 12 is fluidically connected to the first set offive columns 151, raffinate 13 is pumped through each column in thefirst set of five columns 151 in the down-flow direction. The first setof five columns 151 is arranged in parallel so that raffinate 13 enterseach column at the top, flowing through to the bottom. As shown in FIGS.2-4, the discharged raffinate 13 from the first set of five columns 151is collected together and then conveyed (e.g., pumped) through a secondset of five columns 152 arranged in a similar manner to the first set offive columns 151 so that the raffinate 13 enters each column at the top,flowing through to the bottom. As shown in FIGS. 2-4, the columns of thecobalt/nickel/zinc removal ion exchange unit 15 are moving in a firstdirection (e.g., from right to left direction as indicated by arrows38); however, the raffinate 13 is being fed into the first and secondsets of columns 151, 152 in a second direction countercurrent to thedirection of arrows 38 (e.g., left to right as shown on FIGS. 2-4). Itis believed that feeding the raffinate 13 in the second directioncountercurrent to the first direction increases the efficiency of theion exchange resin with which the columns 151-159 are loaded.

Raffinate 13 discharged from the second set of columns 152 is collectedand conveyed to barren tank 30, which is fluidically connected toreceive outflow from the second set of columns 152. Barren tank 30 isfluidically connected to mass balance tank 34″ which is provided so thatthe composition of the discharged raffinate 13 can be determined;however, mass balance tank 34″ is not required. In one embodiment, therewere no detectable amounts of cobalt and nickel in the dischargedraffinate 13 contained in barren tank 30; however, small amounts of zincwere detected (e.g. from about 78 ppm to about 163 ppm). In anotherembodiment shown in FIG. 3, zinc levels may be reduced by sending thedischarged raffinate 13 for a third pass, in a down-flow directionthrough two columns 158 which are arranged in parallel instead ofsending the discharged raffinate 13 directly to barren tank 30, a shownin FIG. 3 Two columns 158 are fluidically to the second set of columns152 from which they receive an intake flow of the discharged raffinate13; the two columns 158 are also fluidically connected to barren tank 30which receives the outflow of raffinate 13 from the two columns 158.

As the ion exchange resin moves through the first and second sets ofcolumns 151, 152, it becomes more fully loaded with cobalt, nickel andzinc to the point of equilibrium between the ion exchange resin andraffinate 13, such that raffinate 13 is at full strength (i.e., cobalt,nickel and zinc have not been removed). Raffinate 13 at full strengthneeds to be displaced from the cobalt/nickel/zinc removal ion exchangeunit 15 to the first set of columns 151. Two columns 153 may be used toachieve the displacement. See FIGS. 2 and 3. The two columns 153 arefluidically connected to cobalt/zinc eluate tank 28 to receivecobalt/zinc eluate as an intake flow. Using cobalt/zinc eluate fordisplacement, as opposed to water, for example, may result in bettercobalt recovery. Since the two columns 153 are loaded with cobalt/zinceluate when the eluting 113 of cobalt and zinc takes place, withoutdilution from water, cobalt concentration is higher. In addition, twocolumns 153 are fluidically connected to an inlet end of the first setof columns 151 so that displaced raffinate 13 mixes with raffinate 13from raffinate tank 12

After full loading of the columns with nickel, zinc and cobalt, thosemetals are stripped by means of eluate system 23. In addition to coppereluent tank 17, eluate system 23 comprises cobalt/zinc eluent tank 27and nickel eluent tank 26. Cobalt/zinc eluent tank 28 and nickel eluenttank 29 are fluidically connected to cobalt/nickel/zinc removal ionexchange unit 15 so that, at the appropriate point, either cobalt/zinceluent or nickel eluent can be added to the cobalt/nickel/zinc removalion exchange unit 15 to strip either nickel or cobalt and zinc from theloaded resin. Since cobalt does not adhere as strongly to the resin asnickel, cobalt may be considered easier to remove than nickel, using anacid concentration weaker than that required to strip the nickel.Therefore, in the embodiments shown in FIGS. 2-4, cobalt and zinc areremoved first. Cobalt/zinc eluent tank 27 is sized for holdingcobalt/zinc eluent which comprises H₂SO₄ in concentration of about 2% toabout 4%, preferably between 2.5% to 3.85% (“weak H₂SO₄”), although weakconcentrations of other strong acids may also be used. In the embodimentshown in FIGS. 2-4, cobalt/zinc eluent comprises H₂SO₄ in concentrationof about 2% to about 3.5%. Cobalt/zinc eluent tank 27 is fluidicallyconnected to four columns 154 connected in series so that thecobalt/zinc eluent enters each column within the four columns 154 at thebottom and exits at the top, as shown in FIGS. 2 and 3. Cobalt and zincare therefore eluted 113 (e.g., stripped) from the bispicolylaminefunctionalized ion exchange resin in solution as copper/zinc eluate.Cobalt/zinc eluate is conveyed to cobalt/zinc eluate tank 28 which isfluidically connected with the last column in the four columns 154 thelast column in the four columns 154 is also fluidically connected tomass balance tank 34″″. Mass balance tank 34″″ allows cobalt/zinc eluateto be analyzed to determine its composition; however, mass balance tank34″″ is not required.

Nickel is the next metal to be eluted 116; however, nickel is to beeluted 116 with nickel eluent which is about 10 times stronger thancobalt/zinc eluent (˜20% v. ˜2%). Therefore, just as the raffinate 13 atfull strength needed to be displaced from the cobalt/nickel/zinc removalion exchange unit, so does the cobalt/zinc eluent (weak H₂SO₄) need tobe displaced. Two columns 155 may be used to achieve the displacement.See FIGS. 2 and 3. The two columns 155 are fluidically connected tonickel eluate tank 28 in series to receive nickel eluate as an intakeflow. Using nickel eluate for displacement, as opposed to water, forexample, may result in better nickel recovery. Since the two columns 155are loaded with nickel eluate when the eluting 116 of nickel takesplace, without dilution, nickel concentration may be higher.

Nickel is next removed. Nickel eluent tank 26 is sized for holdingnickel eluent which comprises H₂SO₄ in concentration of about 20% or 200g/L, although other high concentrations of strong acid could also beused. Nickel eluent tank 26 is fluidically connected to three columns156 connected in series so that the nickel eluent enters each columnwithin the three columns 156 at the bottom and exits at the top, asshown in FIGS. 2 and 3. Nickel is therefore eluted 116 (e.g., stripped)from the bispicolylamine functionalized ion exchange resin in solutionas nickel eluate. Nickel eluate is conveyed to nickel eluate tank 29which is fluidically connected with the last column in the three columns154; the last column in the three columns 154 is also fluidicallyconnected to mass balance tank 34″″. Mass balance tank 34′″ allowsnickel eluate to be analyzed to determine its composition; however, massbalance tank 34′″ is not required.

After nickel is eluted 116, the nickel eluent in the three columns 154is displaced using nickel eluent rinse water. Nickel eluent rinse watertank 36 is sized to hold nickel eluent rinse water and is fluidicallyconnected to three columns 157 in series as shown in FIG. 2. Once thenickel eluent rinse water has displaced the nickel eluent, the nickeleluent in recycled into the eluate system 23. In another embodiment asshown in FIG. 4, displacement of nickel eluent may be achieved by usingdischarged raffinate 13 from barren tank 30. In that embodiment, nickeleluent rinse water tank 36 is eliminated and the three columns 157 inseries are instead fluidically connected to barren tank 30.

In yet another embodiment of apparatus 10, the system for eluting 116nickel is a recycled system in which a single vessel holds nickel eluentand nickel eluate. Nickel eluent/eluate tank 32 is sized to hold bothnickel eluent and the nickel eluate produced through the elution 116 ofnickel in four columns 159. Nickel eluent/eluate tank 32 is fluidicallyconnected to the four columns as shown in FIG. 3. Recirculation of thenickel eluate permits the concentration of nickel to build up in thenickel eluate before recovering the nickel or replacing the combinednickel eluent/eluate solution.

Referring to FIGS. 5 and 6, method 100 for extracting cobalt fromraffinate 13 will now be described. Method 100 comprises providing 101 asupply of raffinate 13. Providing 101 the supply of raffinate maycomprise adding raffinate 13 to process tank 14. Since the embodimentsof method 100 may depend on the constituents in the raffinate 13, method100 comprises analyzing 102 raffinate 13 to determine the composition ofraffinate 13, including identification of the metals and other elementspresent. In one embodiment, raffinate 13 comprises cobalt, copper, ironand nickel. Raffinate 13 also may include other metals, such asmagnesium and zinc. Variously, raffinate 13 analyzed 102 in accordancewith method 100 was determined to contain combinations of copper (about125 to about 150 parts per million (ppm)), cobalt (about 50 to about 55ppm), nickel (about 40 to about 45 ppm), iron (about 500 to about 600ppm total for ferric, ferrous or combined), magnesium (about 7700 ppm)and zinc (about 300 ppm) at pH range from about 1.45 to about 1.8. SeeFIG. 4.

Method 100 further comprises selecting 103 at least one ion exchangeresin to separate out metals from raffinate 13. In an embodiment ofmethod 100, selecting 103 at least one ion exchange resin compriseschoosing a resin with high affinity for nickel and cobalt, such asbispicolylamine. Given that bispicolylamine also has high affinity forcopper such that copper may load preferentially, another ion exchangeresin with high affinity for copper, such as hydroxypropylpicolylaminefunctionalized resin, may also be selected 103 so that copper can beremoved from raffinate 13 before the raffinate 13 comes in contact withbispicolylamine functionalized resin.

Method 100 may further comprise pretreating 105 raffinate 13. Selection103 of various resins may have an effect on what kind of pretreatment105 steps may be necessary or advantageous, if any, because the selectedresins may perform more advantageously under certain conditions. Asdiscussed above, pretreating 105 raffinate 13 may comprise any or all ofthe steps of adjusting 104 (e.g., raising) the pH of raffinate 13,removing 106 any solids produced as a result of the adjusting 104process, or reducing 108 iron from ferric iron to ferrous iron. Inembodiments of method 100, adjusting 104 (e.g., raising) the pH andreducing 108 ferric iron are preferably undertaken prior to removing 100substantially all the copper in the ion exchange system 19, becausecopper catalyzes iron reduction; therefore, it is more likely that ironwould reoxidize if the pH were adjusted 104 after removing 100substantially all the copper. Pretreating 105 the raffinate may beperformed in process tank 14 or in other similar vessels.

Adjusting 104 the pH of raffinate 13 in embodiments of method 100comprises raising the pH of raffinate 13 to between about 3.0 and about3.7, preferably between about 3.0 and 3.5. Depending on the metalspresent in the raffinate 13, as well as the parameters of the ionexchange resin selected 103, other pH levels may be preferred. In theembodiments described herein, raising the pH level of raffinate 13comprises adding CaO, CaCO₃ or other similar compound to raffinate 13 inprocess tank 14 in amounts effective to raise the pH to between about3.0 and about 3.7, preferably between about 3.0 and 3.5; however, otherchemical reagents could also be used as would be familiar to one ofordinary skill in the art after becoming familiar with the teachings ofthe present invention. More specifically, in embodiments of theinvention, CaO may be added to raffinate 13 at a rate of about 2 gramsper liter (g/L) to about 4 g/L; these amounts may vary depending onwhether a continuous feed process or batch process is employed.Adjusting 104 the pH of raffinate 13 may further comprise stirringraffinate 13 during and after addition of CaO, especially where batchprocesses are employed.

Since raising the pH as just described tends to produce solids (e.g.,gypsum) that may clog ion exchange system 19, method 100 may furthercomprise removing 106 solids from raffinate 13. Removing 106 solids maycomprise using a variety of commercially available coagulants andflocculents, such as Nalco N8850 coagulant and N7871, which are added toprocess tank 14 following pH adjustment, causing solids to formcoagulated solids. Removing 106 solids may therefore further comprisefiltering raffinate 13 to remove coagulated and other solids, such asthrough drum filter 16 or other filtering or known physical separationmethods. Removing 106 solids may further comprise additional filtering(e.g., with an inline cartridge filter) prior to removing 110substantially all copper in the ion exchange system 19, as explained inmore detail below.

Given the varying affinities of bispicolylamine for ferric iron (Fe III)and ferrous iron (Fe II) at low pH as shown in FIG. 8, pretreating 105raffinate 13 according to method 100 further comprises reducing 108ferric iron to ferrous iron so that cobalt will load the resinpreferentially instead of iron. Reducing 108 ferric iron to ferrous ironcomprises adding sodium sulfite (Na₂SO₃) to raffinate 13 in an amounteffective to reduce all of the ferric iron to ferrous iron. Na₂SO₃ maybe added at a rate of 1 g/L of raffinate 13 in one embodiment. Ofcourse, if raffinate 13 contains only ferrous iron, no reducing 108 isnecessary.

FIG. 7 also illustrates the high affinity that bispicolylaminefunctionalized resin has for copper; thus, method 100 further comprisesremoving 110 substantially all copper from raffinate 13. Removing 110substantially all copper from raffinate 13 comprises using a first ionexchange resin selective to copper.

The first ion exchange resin may comprise hydroxypropylpicolylaminefunctionalized resin. Using the first ion exchange resin preferablyoccurs prior to absorbing 112 cobalt and nickel using a second ionexchange, such as bispicolylamine functionalized resin. Otherwise, thesecond ion exchange resin will bind preferentially to the copper,leaving no room for cobalt (and nickel) to bind. Removing 110substantially all copper from raffinate 13 comprises feeding raffinate13 (that has been pretreated 105) through copper removal ion exchangeunit 18 as described herein in a manner that permits substantially allcopper to load the first ion exchange resin (e.g.,hydroxypropylpicolylamine functionalized resin) contained in the copperremoval ion exchange unit 18. In an embodiment in which copper removalion exchange unit 18 comprises the fixed bed system of multiple columnsin lead lag configuration, raffinate 13 is pumped into the top of thelead column 21 where it exits through the bottom of the lead column 21and is pumped into the top of lag column 25, exiting lag column 25 freeof substantially all copper. Removing 110 substantially all copper fromraffinate 13 comprises stripping or eluting the copper from the firstion exchange resin and regenerating the beds with copper eluent. Coppereluent may comprise H₂SO₄ or lean electrolyte (containing copper andstrong acid, such as H₂SO₄). In one embodiment, copper eluent is fedthrough the copper removal ion exchange system 18 countercurrent to thefeed direction of raffinate 13. For example, where raffinate 13 is fedin a down-flow direction, copper eluent is fed in an up-flow direction.In one embodiment wherein copper eluent comprises either H₂SO₄ or leanelectrolyte, raffinate 13 is displaced using 20% H₂SO₄ to regenerate thebeds; displacement may be done at a slower flow rate than the rate usedto load the beds with raffinate 13. In yet another embodiment in whichcopper eluent comprises lean electrolyte, 20% H₂SO₄ may be used todisplace the lean electrolyte and water may be used to displace the 20%H₂SO₄ prior to loading the beds again with raffinate 13. In anotherembodiment, water displacement may be employed before using coppereluent to strip the copper.

The copper is recovered as CuSO₄ and is of high purity as shown in FIG.8; thus, recovering 110 substantially all copper in raffinate 13 furthercomprises conveying the copper in solution to the EW tankhouse.

Once substantially all copper has been removed 110, raffinate 13, minusthe copper, is subjected to additional ion exchange processes. Thus,method 100 comprises absorbing 112 cobalt and nickel from raffinate 13using the second ion exchange resin, e.g. bispicolylamine functionalizedresin. In an embodiment in which raffinate 13 further comprises zinc,method 100 comprises absorbing 111 cobalt, zinc and nickel using thesecond ion exchange resin, e.g. bispicolylamine functionalized resin.Absorbing 111 cobalt, zinc and nickel may comprise supplying the columnswith raffinate 13 in a countercurrent direction, as described above.

Once the second ion exchange resin is fully loaded or substantiallyfully loaded, method 100 may comprise eluting 114 the cobalt from thesecond ion exchange resin, e.g., bispicolylamine functionalized resin.Since cobalt does not adhere as strongly to the second ion exchangeresin as does nickel, cobalt may be considered easier to remove thannickel, using an acid concentration weaker than that required to stripnickel. Therefore, in embodiments of method 100, eluting 114 the cobaltfrom the second ion exchange resin comprises using cobalt eluent tostrip the cobalt from the second ion exchange resin. In one embodiment,cobalt eluent comprises weak H₂SO₄ in concentration of about 2% to about4% by volume, preferably between 2.5% to 3.85% by volume; however, otherweak concentrations of other strong acid may also be used. Eluting 114cobalt further comprises removing cobalt in solution after cobalt hasbeen stripped from the second ion exchange resin. Eluting cobalt 114 mayfurther comprise displacing 120 cobalt eluent so that the second ionexchange resin may be regenerated. Displacing 120 cobalt eluent maycomprise using cobalt eluate.

In another embodiment in which raffinate 13 further comprises zinc,eluting 114 cobalt comprises co-eluting 113 cobalt and zinc from thesecond ion exchange resin. Co-eluting 113 the cobalt and zinc from thesecond ion exchange resin comprises using cobalt/zinc eluent to stripthe cobalt and zinc from the second ion exchange resin. In oneembodiment, cobalt/zinc eluent comprises weak H₂SO₄ in concentration ofabout 2% to about 4%, preferably between 2.5% to 3.85%; however, otherweak concentrations of strong acid may also be used. Cobalt/zinc eluentmay be the same substance as cobalt eluent. In an embodiment of method100, cobalt and zinc may remain combined in solution without need forfurther separation. Co-eluting 113 cobalt and zinc may further comprisedisplacing 122 cobalt/zinc eluent so that the second ion exchange resinmay be regenerated. Displacing 122 cobalt/zinc eluent may comprise usingcobalt/zinc eluate.

In another embodiment, co-eluting 113 cobalt and zinc may furthercomprise eluting cobalt 114 and eluting 118 zinc from the copper/zinceluate. In an embodiment, cobalt and zinc may be separated by means ofadditional ion exchange processes using an ion exchange resin that ismore selective for zinc than for cobalt, such as a resin containingaminophosphonic acid (APA) functional groups as may be found inAMBERLITE IRC747 commercially available from The Dow Chemical Company.APA-containing resins are selective for zinc over cobalt.

In another embodiment, cobalt and zinc may be separated by means of ananionic exchange resin, such a DOWEX 21K XLT. In that embodiment,cobalt/zinc eluate may be treated with a salt, such as sodium chloride(NaCl), although other salts could also be used. Addition of a strongbase anionic exchange resin may extract zinc in its anionic form,leaving cobalt in solution.

After the cobalt has been eluted 114 or after the cobalt and zinc havebeen co-eluted 113, method 100 comprises eluting 116 nickel using nickeleluent which comprises H₂SO₄ in concentration of about 20% or 200 g/L;however, high concentrations of other strong acids could also be used.Eluting 116 nickel may further comprise displacing 124 nickel eluent sothat the second ion exchange resin may be regenerated. Displacing 124nickel eluent may comprise using nickel eluate. In another embodiment,eluting 116 nickel may comprise recycling nickel eluent so that thenickel eluent becomes combined with the nickel eluate. The longer therecycling continues, the higher the concentration of nickel eluate, andtherefore, the concentration of nickel in solution, than theconcentration of nickel eluent.

In order to provide further information regarding the invention, thefollowing examples are provided. The examples presented below arerepresentative only and are not intended to limit the invention in anyrespect.

Examples 1-3

Examples 1-3 involved testing of laboratory samples of raffinate 13.

In Example 1, raffinate 13 was made in the lab to test copper recovery;the raffinate 13 comprised copper, ferric iron, nickel, and magnesiumsulfate at a pH of 1.72 to enhance copper loading on thehydroxypropylpicolylamine resin. A column was supplied with 20milliliters (mL) resin and heated to approximately 50° C. The raffinatewas pumped through the column at 20 bed volumes per hour (BV/hr). SeeFIG. 9. Iron and cobalt quickly broke through the bottom of the columnin concentrations higher than their starting concentrations, indicatingthat the metals were displaced from the resin by the more strongly heldcopper. Copper eluted out of the resin between approximately 50 and 80BV and completed loading by 100 BV. The resin was regenerated and coppereluted by rinsing the raffinate out of the resin in the column withwater and then pumping 20% H₂SO₄ through the column at 5 BV/hr. Copperwas successfully eluted and was loaded to 16.3 g/L resin. See FIG. 16.

In Example 2, raffinate 13 comprising ferric iron, nickel, and magnesiumsulfate, and no copper, was prepared in the lab in order to test therecovery of cobalt and separation of cobalt from iron. It was assumedthat raffinate 13 had already had substantially all copper removed 110.In Example 2, the pH of the raffinate was adjusted to a level of 2.8 forthe highest potential of cobalt affinity for bispicolylamine resin. SeeFIG. 7. However, iron precipitated at 2.8 pH and plugged the column sothe testing was stopped.

Example 3, raffinate 13 had the same composition as raffinate 13 inExample 2. Na₂SO₃ was added to raffinate 13 to reduce ferric iron toferrous iron. Following reduction, raffinate 13 was pumped through acolumn of bispicolylamine functionalized resin heated to 50° C. at 20BV/hr. Samples were taken. Cobalt broke through the column at betweenabout 120 and about 140 BV with full breakthrough by 180 BV. Nickel(green band) and cobalt (red/pink band) could be seen as having loadedonto the resin together, with nickel being bound more strongly to theresin than cobalt. Cobalt and nickel were eluted in a two stages toseparate them. Since cobalt is not held to the resin as firmly asnickel, cobalt can be removed with a weaker acid solution; therefore,cobalt was eluted from the resin with 2% H₂SO₄. Nickel was removed using20% H₂SO₄. Some iron eluted with the cobalt which may have resulted formpossible re-oxidation of iron, causing iron to reload on the column asferric iron. Example 3 showed 5.5 g/L of cobalt loading, 6.1 g/L ofnickel loading and 1.7 g/L of iron loading. See FIG. 10.

Examples 4-5

In Examples 4-5, raffinate 13 generated from copper SX at ASARCO's RayMine, Hayden, Ariz. was used for testing copper and cobalt removal.

In Examples 4-5, raffinate 13 was tested using the same procedure forcopper removal as in Example 1 for copper removal; however, since theiron was ferrous iron, no reduction was necessary. Multiple columns ofbispicolylamine resin were placed in series to utilize copper capacityon the lead column without having copper breakthrough the bottom of thefinal column. In Example 4, copper loading occurred at a pH of 1.87 andraffinate 13 was fed through the columns at 20 BV/hr. Copper wasstripped from the resin using 20% H₂SO₄ at the slower flow rate of 5BV/hr. See FIG. 11.

In Example 5, the copper-free raffinate generated during Example 4 wastested for cobalt removal using the same procedure employed in Example3. CaO was added to the copper-free raffinate to achieve a pH of 3.39.Raffinate 13 was filtered to remove solids (e.g., gypsum) and pumpedthrough the resin to recover both cobalt and nickel. Raffinate 13 waspumped through the columns for 90 BV/hr. Raffinate was removed from thecolumns with water. Cobalt and nickel were selectively eluted using 2%H₂SO₄ to strip the cobalt and 20% H₂SO₄ to strip the nickel. The elutioncurve showed significant presence of zinc. See FIG. 12.

Example 6

In Example 6, cobalt removal was tested with lab-prepared raffinate 13comprising zinc, nickel, cobalt, ferrous iron and magnesium sulfate,minus copper and ferric iron, assuming that the steps of removing 110substantially all copper and adjusting 104 the pH of raffinate 13 hadalready been completed. Raffinate 13 was loaded on bispicolylamineresin. Raffinate 13 was rinsed from the resin with water. A method foreluting cobalt, iron and nickel was tested. A solution half saturatedwith sodium chloride (NaCl) was passed through the resin to convert zincto its anionic chloride form. Hydrochloric acid (HCl) (1%) inhalf-saturated NaCl was used to elute cobalt and iron (and some nickel)while keeping the anionic zinc loaded on the resin. The resin, which hasweak base functionality, protonated in the strong acid solution, holdingthe anionic zinc while eluting the cationic cobalt, nickel and iron.Excess chloride was rinsed out of the resin with water, causing zinc toconvert back to its cationic form that was then absorbed again by thechelating groups. 20% H₂SO₄ was used to strip the zinc as well as theresidual nickel that was not removed with HCl. See FIG. 13.

Example 7

Example 7 concerned methods for pH adjustment and iron reduction usingraffinate 13 from the Ray Mine. Based on the results in FIG. 8, it wasdetermined that determined that both steps may occur simultaneouslyprior to copper removal since copper catalyzes the reduction of ironwith sulfite.

Example 9

Cobalt was recovered using bispicolylamine resin at a pH of 2.8. Theseresults demonstrated that cobalt will load on the resin at a pH in arange of about 2.7 to about 3.5.

Example 10

In Example 10, raffinate 13 was pretreated with CaCO₃ to adjust pH to2.75 and with Na₂SO₃ to reduce iron and was filtered. The resin wasloaded with cobalt, nickel and zinc from the pretreated raffinate at 20BV/hr. Elution was done in two steps. Cobalt and zinc were eluted firstwith 2% H₂SO₄; nickel, with 20% H₂SO₄. The cobalt/zinc eluate had acobalt concentration of 1-2 g/L; zinc, a concentration of 2-5 g/L. As asmaller stream, the raffinate 13 had a higher concentration of bothcobalt and zinc than previously observed. FIG. 14.

Example 11

The cobalt/zinc eluate (200 mL) from Example 10 was treated with 1 molar(M) NaCl and passed through 25 mL of a strong base anion exchange resin(e.g. DOWEX 21K XLT) to remove the anionic zinc. Due to the smallamounts involved, zinc was removed, but in small quantities. It may beadvantageous to use multiple and deeper beds of resin in a series toobtain complete zinc removal. See FIG. 15.

Example 12

In Example 12, testing was done on raffinate from the Ray Mine. Avariety of tests were performed.

First, raffinate 13 was tested for organic removal. Because raffinate 13had a pH of 1.75 as shipped, and a pH of 3.0-3.5 after pH adjustment asdescribed herein, organic removal testing was conducted at these two pHlevels. Solids were present when pH was adjusted to 3.4. Testing wasperformed with and without the solids filtered out. An equilibriumisotherm test, or “bottle shake” test, was performed to determine iforganics could be removed from pretreated raffinate. Adsorbent resinDOWEX OPIPORE L493 was used, along with hydroxypropylpicolylamine resinand bispicolylamine resin. The testing was performed at ambienttemperature with 100 mL of raffinate and 1 mL of resin with overnightshaking. Testing for total organic carbon revealed that all three resinsremove some total organic carbon from raffinate 13 with better removalat lower pH.

In a batch process using 400 gallon process tanks containing raffinate13, raffinate underwent pH adjustment 104 by adding 3 g/L CaO; ironreduction 108, by adding 10 g/L Na₂SO₃; and solid removal 106, by adding5 ppm coagulant (N8850). The solution was stirred overnight with asubmersible circulation pump. Although the target pH was 3.0 to 3.5, thenext day, the pH measured 2.7. The pH was adjusted with 1 g/L CaO andstirred for another day, achieving a final pH or 3.7. With the pump on,flocculant (N7871) was added, raffinate 13 was stirred, and then thepump was turned off to settle overnight. Raffinate 13 was then pumpedoff the top of the tank into a clean tote; the feed at the bottom of thetank with the solids was pumped into a separate tote. The pH level wasadjusted further with 3.5 g/L CaO to within the desired range andmeasured 3.4.

Prior to copper removal, an inline cartridge filter was used to filterout any solids to minimized clogging of the resin beds. Copper removalwas tested with two fixed beds of hydroxypropylpicolylamine resin. Eachbed was 2 inches in diameter and about 4.5 feet deep with about 3 L ofresin in each in a lead-lag configuration of columns. Raffinate waspumped into the top of a first column, out the bottom of the firstcolumn, and directly into the top of a second column from which itexited copper free. Sample ports were used to collect samples ofraffinate coming out the bottom of each column. The lead (first) column21 may then be regenerated with acid.

Breakthrough testing for copper removal using a freshly regenerated lagbed and a partially copper loaded lead bed; it showed that copper loadedwell on the hydroxypropylpicolylamine resin using two passes. When thelead bed was nearly completely loaded with copper (100 BV), no coppercould be detected breaking through the lag bed; however, a light bluecolor through the column indicated a small amount of copperbreakthrough. See FIG. 16.

Regeneration of the lead bed with 20% H₂SO₄ was done in a directioncountercurrent to copper loading with raffinate 13 at a flow rate of 8BV/hr. Raffinate 13 was loaded in a down-flow direction and regenerationwas performed in an up-flow direction so that the resin was almostcompletely regenerated when it was being fed with raffinate 13.Regeneration of the resin was performed at a slower rate than the copperloading with raffinate 13 to maximize copper concentration. The majorityof the copper came off the resin in a single bed volume with a maximumconcentration of 25 g/L. The copper loading capacity on the resin wasdetermined to be about 12 g/L. This amount was lower than the totalcapacity of the resin and very selective for the copper over the othermetals in the raffinate as shown in Table 1 below.

TABLE 1 Cu Fe Ni Co Zn Mn Loading 11.99 0.18 0.14 0.01 0.07 0.25 g/LLoading 94.86 1.42 1.11 0.08 0.55 1.98 Metal %The regeneration showed that 95% of the metal on the resin was copper.In other embodiments, there may be more optimization with feeddisplacement with water between the loading and the stripping with acid,such as water displacement with 1 BV/hr. There were no peaks noted foriron, cobalt, zinc or manganese; however, a small amount of nickel wasstripped, as shown in FIG. 17-18.

In one embodiment, copper eluent may comprise lean electrolyte ratherthan clean acid. See, e.g., FIG. 19. Raffinate 13 in the column wouldneed to be displaced with about 1 BV water back to starting point tokeep undesirable metals from contaminating the copper. Copper would thenbe stripped from the column with lean electrolyte and transported to theEW tankhouse. Remaining lean electrolyte would strip a small amount ofcopper, which can be held until the next regeneration and used as thefirst amount of copper eluent. Fresh acid may be used to displace thelean electrolyte and water may be used to displace the acid beforeswitching back to feed.

Example 13

In Example 13, cobalt/zinc removal and nickel removal testing were doneon raffinate 13 from the Ray Mine, using apparatus 10 as shown in FIGS.2-4.

Raffinate 13 that was pretreated 105 with pH adjustment 104, ironreduction 108 and filtering, as well having substantially all copperremoved 110, was subjected to cobalt removal processes using apparatus10 previously described with reference to FIGS. 2-4. With specificreference to FIG. 2, pretreated raffinate 13, with copper removed, wasconveyed from raffinate tank 12 (which, as shown, was a 400-gallon tank)to cobalt/nickel/zinc ion exchange unit 15, comprising a carouselequipped with 24 columns 151-159 loaded with bispicolylaminefunctionalized resin, such as that which has previously been described.The carousel was connected to a multiple port valve and was set on atimer so that the column index rotated regularly around the multipleport valve. Switchboards along the side of the cobalt/nickel/zinc ionexchange unit 15 (e.g., carousel) allowed access to the top and bottomof each column and allowed for the various solutions used during method100 to be supplied to the particular groups of columns at theappropriate times. In one full rotation of the carousel, thebispicolylamine functionalized resin was subjected to loading withraffinate 13, rinsing, and eluting 113, 116. Raffinate 13 was pumpedfrom the raffinate tank 12 through the first set of columns 151, each ina down-flow direction. The first set of columns 151 was arranged inparallel so that raffinate 13 entered each column at the top flowingthrough to the bottom. As shown in FIG. 2, the discharged raffinate 13from each of the first set of columns 151 was collected and then pumpedthrough the second set of five columns 152 arranged in a manner similarto the first set of five columns 151 so that the raffinate 13 enteredeach column at the top, flowing to the bottom of each column in adown-flow direction. As shown in FIGS. 2-4, the columns of the carouselmoved in the first direction (e.g., in a direction from right to left asindicated by arrows 38); however, the raffinate 13 was fed into thefirst and second sets of columns 151, 152 in the second directioncountercurrent to the direction of arrows 38 (e.g., left to right asshown in FIGS. 2-4). It is believed that feeding raffinate 13 in thesecond direction countercurrent to the first direction increasedefficiency of the bispicolylamine functionalized resin with which thecolumns 151-159 were loaded.

Raffinate 13 discharged from the second set of columns 152 was collectedand conveyed to barren tank 30. Some of the discharged raffinate 13 wascollected in mass balance tank 34″ so that its composition could beanalyzed. Mass balance analyses from the several runs tested are listedbelow. In this test, it was determined that since cobalt concentrationlimits were near the detection limit of the x-ray fluorescence detector(XRF), loading was optimized on the more concentrated zinc. Timing ofthe test was based on the point at which the resin was fully loaded. Forthis test, the timing between indexes was 21 minutes.

Moving through the first and second sets of columns 151, 152, thebispicolylamine functionalized resin became more fully loaded withcobalt, nickel and zinc to the point of equilibrium between the ionexchange resin and raffinate 13, such that raffinate 13 was at fullstrength (e.g., cobalt, nickel and zinc have not been removed).Raffinate 13 at full strength therefore needed to be displaced back tothe first set of columns 151. This was accomplished using two columns153 connected in series, as shown in FIGS. 2-4. Cobalt/zinc eluate,which is this example comprised 2% H₂SO₄, as well as already strippedcobalt and zinc. The two columns 153 were connected to cobalt/zinceluate tank 28 so that the two columns 153 received cobalt/zinc eluatein an up-flow direction from left to right countercurrent to thedirection of arrows 38, which is the direction in which the ion exchangeresin indexes, as shown in FIGS. 2-4. Cobalt/zinc eluate was chosen touse for displacement rather than water to avoid dilution so as to keepthe cobalt concentration higher, because the cobalt/zinc are already inthe cobalt/zinc eluate. Again, it is believed that the countercurrentrelationship between the resin indexing and the cobalt/zinc eluate flowincreased the efficiency of the process, reducing the amount of weakH₂SO₄ required.

The bispicolylamine functionalized resin was then stripped withcobalt/zinc eluent comprising weak H₂SO₄. Cobalt/zinc eluent wascontained in cobalt/zinc eluent tank 27 that was fluidically connectedto the four columns 154 connected in series so that the cobalt/zinceluent entered the four columns 154 at the bottom and exited at the top,as shown in FIGS. 2-4. After stripping in the four columns 154, cobaltand zinc were co-eluted 113 in cobalt/zinc eluate which was conveyedfrom the last column of the four columns 154 to cobalt/zinc eluate tank28. Mass balance tank 34″″ allowed for the cobalt/zinc eluate to beanalyzed.

Next, to prepare the system for eluting 116 nickel, the cobalt/zinceluent had to be displaced. Displacement was done with nickel eluatecomprising 20% H₂SO₄ plus stripped nickel for the same reasons thatcobalt/zinc eluate were used for displacement as explained above. Nickeleluate was supplied from nickel eluate tank 28 to two columns 155connected in series, as shown in FIGS. 2-4.

Nickel was eluted 116 next using nickel eluent, which was a strong acid,20% H₂SO₄. Nickel eluent, from nickel eluent tank 26, was supplied tothree columns 156 connected in series so that the nickel eluent enteredeach column at the bottom and exited at the top as shown in FIG. 2.After stripping in the three columns 156, nickel was eluted 116 innickel eluate which was conveyed from the last column of the threecolumns 156 to nickel eluate tank 29. Mass balance tank 34′″ allowed forthe nickel eluate.

After the nickel was eluted 116, the nickel eluent in the three columns157 was displaced using nickel eluent rinse water contained in nickeleluent rinse tank 36. Nickel eluent rinse tank 36 was connected to thethree columns 156 arranged in series so that the nickel eluent rinsewater entered each column at the bottom and exited at the top as shownin FIG. 2. The displaced nickel eluent was fed back into the elutioncircuit to minimize waste.

The system of Example 13 was run several times before collectingcomposition data. After that several mass balance runs were performed toanalyze the composition of raffinate 13 entering the system, andraffinate, as well as cobalt/zinc eluate and nickel eluate, exiting ateach point in the system. With additional testing, cobalt concentrationin the cobalt/zinc eluate continued to increase, while nickel and ironconcentrations were low. Nickel stripped with the cobalt appeared to berelated to the acid strength of the cobalt/zinc eluent stripping acidstrength, which seemed to be best balanced under the operatingconditions tested where cobalt/zinc eluent comprised about 3.5% H₂SO₄.

Mass Balance 1

Upon start-up, cobalt/zinc eluate began traveling to the left on theswitchboard. Therefore, the flow rate of the cobalt/zinc eluent wasincreased several times. The acid concentration of the cobalt/zinceluent was also checked and increased. While the original concentrationwas 2.5%, this was increased to 3.85% by adding more acid. The increasein concentration provided better results. The iron loading was low;however, iron re-oxidization may have occurred due to a several-weekinterval between copper removal and this mass balance test. In anembodiment, low iron loading may be remedied by further lowering the pHof the raffinate 13 level to obtain better reducing action from Na₂SO₃.

Results

-   -   Mass Balance Tank 34″: Discharged raffinate/barren looked good        (XRF data)        -   Co=0 ppm        -   Ni=0 ppm        -   Zn=22 ppm        -   Fe=497 ppm (raffinate was 506 ppm)    -   Mass Balance Tank 34″″: Co/Zn eluate was slightly contaminated        -   Co=633 ppm        -   Ni=396 ppm        -   Zn=3378 ppm        -   Fe=531 ppm (raffinate was 506 ppm)    -   Mass Balance Tank 34″″: Ni eluate contained only Ni (352 ppm)    -   Overall metal loading on the resin was lower than expected        -   Co=1.91 g/L        -   Ni=1.72 g/L        -   Zn=10.19 g/L        -   Fe=1.60 g/L        -   Total=15.42 g/L        -   Expected˜20 g/L

Mass Balance 2

Following the Mass Balance 1 test, changes were made to apparatus 10, aswell as method 100. As shown in FIG. 4, nickel eluent rinse water tank36 was removed. Instead, a pump was added so that displaced raffinate 13from barren tank 30 could be used for displacement. As shown in FIG. 4,barren tank 30 was then connected to three columns 157 in series so thatdisplaced raffinate 13 from barren tank 30 could be pumped into eachcolumn so that it entered at the bottom and exited at the top. After onepass, it appeared that the resin was not fully loaded by the time theresin exited the loading zone in the first and second set of columns151, 152. Therefore, three passes were used before moving the columns totry to get the loading higher.

Results

-   -   Mass Balance Tank 34″: Discharged raffinate/barren contained        more Zn after running loading zone without indexing (XRF data)        -   Co=0 ppm        -   Ni=0 ppm        -   Zn=78 ppm        -   Fe=544 ppm    -   Mass Balance Tank 34″″: Co/Zn eluate was cleaner        -   Co=703 ppm        -   Ni=353 ppm        -   Zn=2827 ppm        -   Fe=350 ppm    -   Mass Balance Tank 34′″: Ni Eluate contained Ni and Fe        -   Ni=352 ppm        -   Fe=31 ppm    -   Overall metal loading on the resin was lower than Mass Balance        1, but cobalt loading was slightly higher        -   Co=2.03 g/L        -   Ni=1.47 g/L        -   Zn=8.16 g/L        -   Fe=1.05 g/L        -   Total=12.71 g/L

Mass Balance 3

Following Mass Balance 2, two changes were made to apparatus 10 andmethod 100 for Mass Balance 3. Because nickel concentration in thenickel eluate was low with a lot of 20% H₂SO₄ containing a few ppm ofnickel, nickel elution 116 was converted to a re-circulation system toallow nickel concentration to build up over time. When nickelconcentration reaches a high level, the entire nickel eluent/eluatecould be replaced with fresh acid, or some nickel eluent/eluate could beremoved and replenished with fresh acid to allow nickel to continue tobe stripped. Thus, as shown in FIG. 3, nickel eluent tank 26 and nickeleluate tank 29 were removed. In the spot previously occupied by nickeleluate tank 29, nickel eluent/eluate tank 32 was inserted to hold boththe nickel eluent and the nickel eluate which were recycled. However,nickel eluent/eluate tank 32 was connected to four columns 159 as shownin FIG. 3. Another change was made, this time to the loading section.From previous tests, it appeared that metal was getting through theloading section as evidenced by high zinc which may be correlated withthe presence of cobalt. As shown in FIG. 3, two columns 158 were addedto accommodate the discharged raffinate 13 from the second set ofcolumns 152. The entire flow of discharged raffinate 13 was fed throughthe two columns in parallel as shown in FIG. 3. The result was not onlyto collect trace metal left in the discharged raffinate 13, but also todisplace any nickel eluent/eluate left in the column. The same pumpadded in FIG. 4 to pull discharged raffinate 13 from barren tank 30 forrinsing was also used to balance the re-circulated regeneration of thenickel, as well as weak acid displacement from the cobalt/zincco-eluting 113 process.

Results

-   -   Mass Balance Tank 34″: Discharged raffinate/barren contained        more Zn after running loading zone without indexing (XRF data)        -   Co=0 ppm        -   Ni=0 ppm        -   Zn=107 ppm        -   Fe=652 ppm    -   Mass Balance Tank 34″″: Co/Zn Eluate had higher Co        -   Co=898 ppm        -   Ni=530 ppm        -   Zn=3622 ppm        -   Fe=362 ppm    -   Mass Balance Tank 34′″: Ni eluate contained Ni and Fe        -   Ni=468 ppm        -   Fe=120 ppm    -   Overall metal loading on the resin was lower, but mostly due to        less Fe and Zn        -   Co=1.76 g/L        -   Ni=1.16 g/L        -   Zn=7.10 g/L        -   Fe=0.69 g/L        -   Total=10.72 g/L

Mass Balance 4

Mass balance 4 was conducted using apparatus 10 as shown in FIG. 3. Inprevious tests, more iron appeared in the cobalt eluate than expected.It was believed that iron may have resulted from failure to displace allraffmate 13 in the column. Since manganese does not load on the resinand was present in fairly high concentration in raffinate 13, it wasbelieved that manganese would be a good marker for raffinate 13 in thecobalt eluate. To control this, the pumps for the cobalt elution 114 andraffinate 13 recovery were better balanced. The raffmate recovery pumpwas turned up to ensure no raffinate 13 made it into the cobalt eluate.No raffinate 13 showed up in the cobalt eluate since manganese and ironconcentrations were 0 ppm. Since nickel appeared in the cobalt eluate,the cobalt/zinc eluent was slightly diluted in an attempt to strip lessnickel at this step. The cobalt/zinc eluent acid concentration wasdropped from 3.85% to 3.37% H₂SO₄.

Results

-   -   Mass Balance Tank 34″: Discharged raffinate/barren (XRF data)        -   Co=0 ppm        -   Ni=0 ppm        -   Zn=96 ppm        -   Fe=628 ppm        -   Mn=836 ppm (838 ppm in the feed)    -   Mass Balance Tank 34″″: Co/Zn eluate had much higher Co and no        entrained raffinate        -   Co=1616 ppm        -   Ni=524 ppm        -   Zn=6640 ppm        -   Fe=0 ppm        -   Mn=0 ppm    -   Mass Balance Tank 34′″: Ni eluate continued to increase in        concentration; Fe is near the detection limit        -   Ni=932 ppm        -   Fe=0 ppm    -   Overall metal loading on the resin was similar        -   Co=1.99 g/L        -   Ni=0.93 g/L        -   Zn=8.17 g/L        -   Fe=0 g/L        -   Total=11.09 g/L

Mass Balance 5

In mass balance 5, cobalt concentration continued to increase in thecobalt eluate, and the nickel concentration was lower which may havebeen due to the lower acid concentration of the cobalt/zinc eluent. Irondid load on the resin although there was no raffinate entrained as shownby lack of manganese in the cobalt eluate. Likely, this may haveresulted from reoxidization of the iron during intervals between tests.

Results

-   -   Mass Balance Tank 34″: Discharged raffinate/barren (XRF data        unless noted)        -   Co=6.42 ppm (Raffinate Co=47.57; both numbers by AA)        -   Ni=0 ppm        -   Zn=163 ppm        -   Fe=596 ppm        -   Mn=853 ppm    -   Mass Balance Tank 34″″: Co/Zn eluate had higher Co, but some Fe        -   Co=2076 ppm        -   Ni=216 ppm        -   Zn=7373 ppm        -   Fe=552 ppm        -   Mn=0 ppm    -   Mass Balance Tank 34′″: Ni Eluate continued to increase in        concentration; Fe is near the detection limit        -   Ni=1144 ppm        -   Fe=38 ppm    -   Overall metal loading on the resin was lower        -   Co=1.85 g/L        -   Ni=0.23 g/L        -   Zn=6.53 g/L        -   Fe=0.52 g/L        -   Total=9.12 g/L

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those of ordinary skill in theart from this disclosure that various changes and modifications can bemade herein without departing from the scope of the invention as definedin the appended claims. For example, the size, shape, location ororientation of the various components disclosed herein can be changed asneeded or desired. Components that are directly connected may haveintermediate structures between them. The functions of two or moreelements or units may be performed by one and vice versa. Thestructures, steps, and functions of one embodiment may be adopted inanother embodiment. It is not necessary for all advantages to be presentin a particular embodiment at the same time. In addition, terms ofdegree such as “substantially,” “about,” and “approximate” as usedherein mean a reasonable amount of deviation of the modified term suchthat the result would not be changed. For example, these terms can beconstrued as including a deviation of at least ±5% of the modified termif this deviation would not negate the meaning of the term it modifies.Thus, it is contemplated that the inventive concepts herein describedmay be variously otherwise embodied and it is intended that the appendedclaims be construed to include alternative embodiments of the invention,except insofar as limited by the prior art.

1. A method of ion exchange cobalt recovery from raffinate, comprising:producing raffinate, the raffinate including at least cobalt, zinc,copper, nickel and ferric iron; raising a pH of the raffinate; removingsolids from the raffinate; reducing ferric iron to ferrous iron; loadinga copper recovery ion exchange unit with an ion exchange resin selectivefor copper; feeding the raffinate into the copper recovery ion exchangeunit in a first direction; regenerating the copper recovery ion exchangeunit to recover substantially all the copper from the ion exchange resinselective for copper; loading a cobalt/nickel/zinc recovery ion exchangeunit with a second ion exchange resin selective at least for cobalt;feeding the raffinate into the cobalt/nickel/zinc recovery ion exchangeunit in the first direction, the second ion exchange resin holdingcobalt, zinc and nickel; displacing the raffinate from thecobalt/nickel/zinc recovery ion exchange unit; feeding cobalt/zinceluent into the cobalt/zinc/nickel recovery ion exchange unit to elutethe cobalt and zinc in a cobalt/zinc solution; displacing thecobalt/zinc eluent in the cobalt/zinc/nickel recovery ion exchange unit;and feeding nickel eluent into the cobalt/zinc/nickel recovery ionexchange unit to elute the nickel.
 2. The method of claim 1, wherein theregenerating comprises feeding a strong acid into the copper recoveryion exchange unit in a second direction, the second direction beingcountercurrent to the first direction.
 3. The method of claim 1, whereinthe feeding the raffinate into the copper removal ion exchange unitcomprises feeding at a first rate and wherein the regenerating comprisesregenerating at a second rate, the second rate being slower than thefirst rate.
 4. The method of claim 1, wherein the ion exchange resinselective for copper is a hydroxypropylpicolylamine resin.
 5. The methodof claim 1, further comprising displacing the nickel eluent.
 6. Themethod of claim 5, wherein the displacing the nickel eluent comprisesone selected from the group consisting of displacing with water,displacing with nickel eluent, and displacing with recycled nickeleluent/eluate.
 7. The method of claim 1, wherein the second ion exchangeresin is a bispicolylamine functionalized resin.
 8. The method of claim1, wherein the feeding cobalt/zinc eluent comprises feeding cobalt/zinceluent in a second direction, the second direction being countercurrentto the first direction.
 9. The method of claim 1, further comprisingseparating the zinc from the cobalt in the cobalt/zinc solution.
 10. Themethod of claim 9, wherein the separating comprises using a basic anionexchange to remove anionic zinc.
 11. The method of claim 10, wherein theseparating comprises adding a salt to the cobalt/zinc solution.
 12. Themethod of claim 1, wherein the raising the pH of the raffinate comprisesraising the pH to between about 3.0 and about 3.5.
 13. The method ofclaim 1, wherein the removing solids from the raffinate comprisesfiltering the raffinate.
 14. The method of claim 1, wherein the raisingthe pH of the raffinate comprises adding calcium oxide or calciumcarbonate to the raffinate.
 15. The method of claim 1, wherein thereducing ferric iron comprises adding sodium sulfite to the raffinate.